Reversing valve for refrigeration systems and air conditioning systems



Dec. 27, 1966 F. A. GREENAWALT 3,293,880

REVERSING VALVE FOR REFRIGERATION SYSTEMS AND AIR CONDITIONING SYSTEMS Filed Sept. 16, 1965 2 Sheets-Sheet 2 FRED A GREENAWALT United States Patent 3 293,880 REVERSKNG VALVE ll- OR REFRIGERATION SYS- TEMS AND AIR CONDITiONING SYSTEMS Fred A. Greenawait, Pompano Beach, Fla., assignor to Lyle A. Trolz, Fort Lauderdale, Fla. Filed Sept. 16, 1965, Ser. No. 487,777 9 Claims. (Cl. 62-324) This invention relates generally to refrigeration and air conditioning systems, such as the systems utilized in refrigerators and air conditioners, and more particularly to an improved reversing valve for such systems which is operable to selectively reverse the order of flow of refrigerant through the heat exchangers which function as the condenser and evaporator in a compressor-condenser-expander-type refrigeration system.

Provision is made in some refrigeration systems for selectively reversing the direction of refrigerant fiow in order to effect periodic heating of a particular heat exchanger in the system by changing the function of that heat exchanger from an evaporator to a condenser for the purpose of quickly melting frost or ice which may have collected thereon, in the case of a refrigerator, or heating the interior of a room during cooler periods of weather, in the case of an air conditioner. The term refrigeration systems, as used hereinafter, is inclusive of air conditioning systems. Presently available reversing valves capable of installation in refrigeration systems for effecting flow reversal are not completely satisfactory. Most of these valves utilize a shiftable piston slidably mounted in a cylinder and arranged so that transversely opposite sides of at least portions of the piston are exposed to the large differential pressure existing between the discharge and suction refrigerant in the system. This differential pressure creates a frictional force between one side of the cylinder and the piston which must be overcome in order to move the piston axially so as to cause it to reverse the flow of refrigerant. This requirement for a large shifting force necessitates the use of a large diameter piston to provide a sufficiently large area to develop the necessary thrust to move the piston. The use of such large pistons is objectionable from the standpoint of cost and also from the standpoint of wear. It is an object of this invention, therefore, to provide a reversing valve for refrigeration systems which utilizes a floating piston, namely, a piston arranged in the system so that aside from its own weight it is completely balanced in the system and the only friction developed between the piston and cylinder in which it moves is that due to the weight of the piston.

A further object of this invention is to provide a reversing valve for refrigeration systems which is compact, economical to manufacture, and utilizes the main flow of refrigerant fluid from the compressor in the system to reverse the valve.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIGURE 1 is a schematic illustration of a refrigeration system, showin the reversing valve of this invention assembled in the system and in a position in which it provides for flow of refrigerant in one direction through the heat exchangers in the system, with the reversing valve and certain parts of the system being shown in section for the purpose of clarity;

FIGURE 2 is a transverse sectional view of the reversing valve of this invention looking substantially along the line 22 in FIG. 1; and

FIGURE 3 is a schematic illustration like FIG. 1 showing the reversing valve of this invention in a position for reversing the flow of refrigerant through the heat exchangers in the system.

With reference to the drawing, the improved reversing valve of this invention, indicated generally at 10, is illustrated in FIG. 1 is a refrigeration system 12 which includes a conventional compressor 14, and heat exchangers 16 and 18. A conventional flow restriction tube 20 connects the heat exchangers 16 and 18, both of which are capable of functioning either as a condenser or an evaporator. The compressor 14 has its discharge connected by a conduit 22 to the inlet 24 for the reversing valve 10. A conduit 26 connects an outlet port 28 for the reversing valve 10 with the suction inlet of the compressor 14.

In the illustrated embodiment of the invention, the valve 10 consists of a tubular valve body 30 closed at its ends by end plates 32 and 34 and formed intermediate its ends with the discharge port 28. A pair of ports 36 and 38 are formed in the valve body 36 on opposite sides of the discharge port 28, with the port 36 being connected by a conduit 40 to the heat exchanger 16, and the port 38 being connected by a conduit 42 to the heat exchanger 18. Adjacent the end plate 32, the valve body 30 is formed with an inlet port 44, connected to a short inlet pipe 46, and adjacent the end plate 34, the valve body 30 is formed with another inlet port 50 which is similarly connected to a short inlet pipe 52.

A valve tube 54, of a length corresponding substantially to the length of the valve body 30, is mounted on the inlet pipes 46 and 52. One end of the valve tube 54 is closed by an end plate 56, and adjacent its opposite end the valve tube 54 is provided with a pair of spaced internal valve seats 58 and 60. Between the valve seats 58 and 60, the valve tube 54 is connected to the inlet conduit 24 for the valve 10.

A solenoid assembly 62 is mounted on one end of the valve tube 54. The valve assembly 62 includes a plunger sleeve 65 which is secured by a brazed joint for hermetic sealing purposes in the open end of the valve tube 54 at a position such that the inner end of the sleeve 65 forms the seat 60. A solenoid coil 64 is mounted on the sleeve 65 so that it surrounds a hollow plunger 66 which acts as an armature. A spring 70, positioned in a cavity 68 in the plunger 66 and bearing at one end on a plug 72 fitted in the sleeve 65, normally urges the plunger 66 toward the right as viewed in FIGS. 1 and 3. A stem 74 formed integral with the plunger 66 is provided at one end with a valve piston 76 of a size to seat on the seats 58 and 60. The coil 64 is connected in a suitable circuit such that when the circuit is open, and the coil 64 is de-energized, the spring 70 will move the valve piston 76 into engagement with the seat 58. When the circuit is closed so as to energize the coil 64, the plunger 66 is pulled to the left as viewed in FIG. 1 so as to move the valve piston 76 into engagement with the seat 60 as illustrated in FIG. 3. engaged with the seat 58 as shown in FIG. 1, refrigerant entering the valve 10 through the inlet 24 will flow around the valve stem 74 and into the valve body 30 through the inlet port 50. When the valve member 76 is shifted to a seated position on the seat 60, refrigerant entering the valve 10 through the inlet 24 will flow into the valve body 30 through the inlet port 44. Some leakage takes place around the valve member 76 to keep the pressure balanced on both sides.

A free floating piston 80 is slidably supported in the cylindrical passage 82 formed by the inner wall of the tubular valve body 30 as shown in FIGS. 1 and 3. The The piston 80 is of one-piece construction and has two axially spaced cylinder portions 84 and 86, of a diameter 'to be slidably supported in the valve body 30, and a reduced diameter stern portion 88 which connects the cyl Thus, with the valve plunger 76 inder portions 84 and 86. The cylinder' portion 84 is formed with an axially outwardly extending projection 90 and the cylinder portion 86 is similarly formed with an axially outwardly extending projection 92. The projection 90 is formed with an axially inwardly extending opening 94 which communicates at its inner end with a radially outwardly extending passage 96 formed in the cylinder portion 84 at a position such that it terminate at its outer end in an annular groove 98 formed in the outer surface of the cylinder portion 84. Projection 92 (FIGS. 1 and 2) is similarly formed with an axial passage which communicates at its inner end with a radially outwardly extending passage 102 that communicates with a groove 104 formed in the cylinder portion 86 intermedi ate the ends thereof. The purpose of the projections 90 and 92, is to limit the movement of the piston 80 toward the end plates 32 and 34 to positions in which the piston 80 will not completely close the inlet port 44 (FIG. 1) or the inlet port 50 (FIG. 1).

In the operation of the reversing valve 10 in the system 12, assume that the solenoid coil 64 is not energized so that the valve piston 76 is seated on seat 58 as shown in FIG. 1. In this position of valve piston 76, refrigerant entering the valve 10 through the inlet 24 flows through the inlet port 50 into the valve body 30, and out the valve body 30 through the port 36. The refrigerant from port 36 then flows through the conduit 40, through the heat exchanger 16, which then functions as a condenser, through the restricting tube and through the heat exchanger 18 which then functions as an evaporator. From the heat exchanger 18, the refrigerant flows through the conduit 42 and back into the valve body through the port 38. Because the piston unit 80 is in the position illustrated in FIG. 1, the port 38 communicates with the valve discharge port 28 through the chamber 110 formed by the portion of valve body 30 between the cylinder portions 84 and 86. The refrigerant then returns to the compressor 14 through the suction line 26.

When it is desired to reverse the flow of refrigerant through the heat exchangers 16 and 18 so that the heat exchanger 16 will function as an evaporator and the heat exchanger 18 as a condenser, the circuit for the coil 64 is closed so that the coil is energized to thereby retract the plunger 66 against the pressure of the spring 70 to a position in which the valve piston 76 seats on the seat 60. Communication of refrigerant entering the valve 10 through the inlet 24 with the valve body inlet pipe 52 is then blocked by the valve piston 76. Consequently, this refrigerant flows through the inlet pipe 46 into the valve body 30 through the inlet port 44. The pressure of this refrigerant on the cylinder portion 86 moves the piston 80 toward the left from its position shown in FIG. 1 toward its position shown in FIG. 3. As soon as the piston 80 is moved to a position in which it cuts off communication of the inlet port 50 and the port 36, fluid in the valve body 30 between the end plate 34 and the piston 80 flows through the path provided by the internal piston passages 94 and 96 and the groove 98 to the port 36. Since the main flow of refrigerant from the compressor discharge conduit 22 is being utilized to shift the piston 80, it is moved rapidly from its FIG. 1 to its FIG. 3 position and across port 38 so as not to impede flow through port 38.

As shown in FIG. 3, when the piston 80 has been thus shifted, it acts to communicate the inlet port 44 to the valve body 30 with the discharge port 38, and communicate the port 36 with the valve discharge port 28 through the chamber 110. As a result, in the FIG. 3 position of the piston 80, the functions of the heat exchangers 16 and 18 have been reversed from their functions in the FIG. 1 position of the piston 80. When it is desired to return the piston unit 80 to its FIG. 1 position, the circuit for the coil 64 is opened so that the coil is de-energized, causing the spring 70 to move the valve piston 76 back onto the seat 58, as shown in FIG. 1. Communication of the valve inlet 24 with the valve body inlet port 44 is then blocked by the valve piston 76 so that the inlet refrigerant flows into the valve body 30 through the inlet port 50, causing the piston 80 to move toward the right as viewed in FIG. 3. As the piston 80 closes port 38, fluid in body 30 between the piston 80 and flows through the passages 100, 102 and the groove 184 into the port 38, to allow for a quick movement of the piston 80 to the position illustrated in FIG. 1 in which port 36 is open.

It can thus be seen that the piston 80 is quickly shifted between its FIG. 1 and FIG. 3 positions so as to reverse the functions of the heat exchangers 16 and 18 because the main flow of refrigerant from the compressor 14 is being utilized to shift the piston 80. Furthermore, once the position of the valve piston 76 is shifted, the valve unit 80 is completely balanced except for the force of the refriger ant from the compressor discharge line 22 on one end of the piston 80. In other words, there is no force applied at any time to the piston 80 which would tend to urge it against one side of the valve body 30 so as to create a frictional force on piston 80 which must be overcome in order to move it axially between its limit positions shown in FIGS. 1 and 3. Whatever fluid forces are applied to the piston 80 by the fluid which is in the chamber are completely balanced because the piston connecting portion 88 is spaced from the valve body 30 so that the fluid surrounds portion 88. As a result, a relatively small piston 80 can be employed, thereby enabling economical manufacture of the valve 10 in small sizes. In a preferred embodiment of the invention, the piston 80 is of about one-half inch in diameter.

It will be understood that the reversing valve for refrigeration systems which is herein disclosed and described is presented for purposes of explanation and illustration and is not intended to indicate limits of the invention, the scope of which is defined by the following claims.

What is claimed is:

1. In a reversible cycle refrigerant system having a compressor, and a pair of heat exchangers connected in a circuit, a reversing valve for selectively reversing the order of flow of refrigerant through said heat exchangers, said valve comprising a hollow valve body having a first port intermediate the ends thereof connected to the intake of said compressor, said valve body having a pair of ports on opposite sides of said first port connected to said pair of heat exchangers, said valve body having a pair of inlet openings spaced longitudinally thereof on opposite sides of said ports, means for selectively connecting the discharge side of said compressor to one or the other of said inlet openings, a piston mounted for free sliding movement in said valve body between a pair of limit positions said piston cooperating with said valve body to form a chamber intermediate the ends of said piston shaped so that forces applied to said piston by fluid in said chamber are substantially balanced, said piston in one of said limit positions being located so that said chamber communicates said first port with one of said pair of ports and in the other one of said limit positions communicates said first port with the other one of said pair of ports, said piston in each of said limit positions being located to one side of one of said inlet openings and providing for communication of said one inlet opening with one of said pair of ports.

2. In a reversible cycle refrigerant system having a compressor, and a pair of heat exchangers connected in a circuit, a reversing valve for selectively reversing the order of flow of refrigerant through said heat exchangers, said valve comprising a tubular valve body having a first port intermediate the ends thereof connected to the intake of said compressor, said valve body having a pair of ports on opposite sides of said first port connected to said pair of heat exchangers, said valve body having a pair of inlet openings spaced longitudinally thereof on opposite sides of said ports, means for selectively connecting the discharge side of said compressor to one or the other of said inlet openings, a piston mounted for free sliding move ment in said valve body between a pair of limit positions, said piston having a pair of axially spaced cylinder portions of a diameter corresponding substantially to the internal diameter of said valve body and a connecting portion which extends between said cylinder portions and is spaced from said valve body, said piston cooperating with said valve body to form a chamber therein between said cylinder portions and surrounding said connecting por tion, said piston in one of said limit positions being located so that said chamber communicates said first port with one of said pair of ports and in the other one of said limit positions communicates said first port with the other one of said pair of ports, said piston in each of said limit positions being located to one side of one of said inlet openings and one of said pair of ports and providing for communication of said one inlet opening with said lastmentioned one of said pair of ports.

3. In a reversible cycle refrigerant system having a compressor, a condenser and an evaporator connected in a circuit, a reversing valve for selectively reversing the order of flow of refrigerant through the condenser and evaporator, said valve comprising a tubular valve body having a first port intermediate the ends thereof connected to the intake of said compressor, end plates on said body closing the ends thereof, said valve body having a pair of ports on opposite sides of said first port connected to said condenser and said evaporator, said valve body having a pair of inlet openings spaced longitudinally thereof on opposite sides of said ports, means for selectively connecting the discharge side of said compressor to one or the other of said inlet openings, a piston mounted for free sliding movement in said valve body between a pair of limit positions, said piston having a pair of axially spaced cylinder portions of a diameter corresponding substantially to the internal diameter of said valve body and a connecting portion which extends between said cylinder portions and is spaced from said valve body, said piston cooperating with said valve body to form a chamber therein between said cylinder portions and surrounding said connecting portion, projections on said cylinder portions, engageable with said end plates to define said limit positions, pass-age means in each of said projections and cylinder portions providing for a flow of fluid from said body through said passage means for preventing trapping of fluid in said body between said piston and an end plate as said piston approaches the end plate, said piston in one of said limit positions being located so that said chamber communicates said first port with one of said pair of ports and in the other one of said limit positions communicates said first port with the other one of said pair of ports, said piston in each of said limit positions being located to one side of one of said inlet openings and one of said pair of ports and providing for communication of said one inlet opening with said last-mentioned one of said pair of ports.

4. In a reversing valve for a reversible cycle refrigerant system, a valve body having a cylindrical passage therein, said body being provided with a first port communicating with said passage intermediate the ends thereof and a pair of ports disposed on opposite sides of said first port and communicating with said passage, a piston slidably mounted in said passage for movement axially thereof between a pair of limit positions, said piston being comprised of a pair of cylindrical end portions spaced axially of said passage and a connecting portion which extends between said cylindrical portions and is spaced from the walls of said passage suificiently to permit flow of fluid in said passage about said connecting portion, said cylindrical portions being spaced such that in each limit position of said piston said first port communicates with one of said pair of ports through said passage between said cylindrical end portions and one of said end portions blocks communication of said first port with the other one of said pair of ports.

5. A reversing valve for a reversible cycle refrigerant system, said valve comprising a valve body having a cylindrical passage therein, said body being provided with a first port communicating With said passage intermediate the ends thereof and a pair of ports disposed on opposite sides of said first port and communicating with said passage, a piston slidably mounted in said passage for movement axially thereof between a pair of limit positions, said piston being comprised of a pair of cylindrical end portions spaced axially of said passage and a connecting portion which extends between said cylindrical portions and is spaced from the walls of said passage sufficiently to permit flow of fluid in said passage about said connecting portion, said cylindrical portions being spaced such that in each limit position of said piston said first port communicates with one of said pair of ports through said passage between said cylindrical end portions and one of said end portions blocks communication of said first port with the other one of said pair of ports, said valve body having inlet ports disposed at opposite ends of said piston, a valve tube having an inlet adapted to be supplied with fluid under pressure, said tube communicating with said valve body inlet ports, and valve means in said valve tube movable between two positions for selectively communicating said inlet with either of said inlet ports to shift said piston between said limit positions.

6. A reversing valve according to claim 5 further including solenoid means connected to said valve means for moving said valve means between the two positions therefor.

7. In a valve, a valve body having a substantially straight passage therein, means on said body defining the ends of said passage, a pair of fluid inlets communicating with said passage adjacent the ends thereof, means for supplying fluid under pressure to said passage only through one or the other of said inlets, a piston slidably supported in said passage for movement between a first limit position at one end of said passage and a second limit position at the other end of said passage, said inlets being located so that they are in fluid communication with opposite ends of said piston in both limit positions of said piston.

8. In a reversing valve for a refrigerant system which includes a compressor, a valve body having a substantially straight passage therein, means on said body defining the ends of said passage, a pair of fluid inlets communicating with said passage adjacent the ends thereof, means for supplying fluid under pressure from said compressor to said passage only through one or the other of said inlets, a piston slidably supported in said passage for movement between a first limit position at one end of said passage and a second limit position at the other end of said passage, said inlets being located so that they are in fluid communication with opposite ends of said piston in both limit positions of said piston, said piston being formed so that it has a pair of spaced cylinder shape end portions connected by a reduced diameter concentric connecting portion, and a plurality of ports in said body some of which are communicated through said body and between said cylinder portion in both limit positions of said piston.

9. In a reversible cycle refrigerant system having a compressor, and a pair of heat exchangers connected in a circuit, a reversing valve for selectively reversing the order of flow of refrigerant through said heat exchangers, said valve comprising a hollow valve body having a first port intermediate the ends thereof connected to the intake of said compressor, said valve body having a pair of ports on opposite sides of said first port connected to said pair of heat exchangers, said valve body having a pair of inlet openings spaced longitudinally thereof on opposite sides of said ports, a valve tube mounted on said valve body and communicating adjacent the ends thereof with said inlet openings, means closing one end of said valve tube, a plunger tube projected into the opposite end of said valve tube so as to be mounted thereon, the inner end of said plunger tube forming a first valve seat located between the ends of said valve tube, means forming a second seat in said valve tube between the ends thereof and spaced from said first seat, a valve plunger slidably mounted in said plunger tube and provided With a piston movable between positions engaged with said first and second seats, a solenoid coil surrounding said plunger tube so that on energization of said coil said valve piston is moved into engagement with one of said seats, spring means for moving said valve piston into engagement with the other one of said seats when said coil is de-energized, means connecting the discharge side of said compressor to said valve tube at a position between said valve seats so that the energized or de-energized condition of said coil determines the one of said pair of valve body inlets which is communicated with refrigerant from the discharge side of said compressor, a piston unit mounted for free sliding movement in said valve body between a pair of limit positions, said piston unit cooperating with said valve body to form a chamber intermediate the ends of said piston unit shaped so that forces applied to said piston unit by fluid in said chamber are substantially balanced, said piston unit in one of said limit positions being located so that said chamber communicates said first port with one of said pair of ports and in the other one of said limit positions communicates said first port with the other one of said pair of ports, said piston unit in each of said limit positions being located to one side of one of said inlet openings and providing for communication of said one inlet opening with one of said pair of ports.

References Cited by the Applicant UNITED STATES PATENTS 2,714,394 8/1955 Moran 62--l60 2,991,631 7/1961 Roy 62-324 3,204,420 9/1965 Lurn 62324 WILLIAM J. WYE, Primary Examiner. 

1. IN A REVERSIBLE CYCLE REFRIGERANT SYSTEM HAVING A COMPRESSOR, AND A PAIR OF HEAT EXCHANGERS CONNECTED IN A CIRCUIT, A REVERSING VALVE FOR SELECTIVELY REVERSING THE ORDER OF FLOW OF REFRIGERANT THROUGH SAID HEAT EXCHANGERS, SAID VALVE COMPRISING A HOLLOW VALVE BODY HAVING A FIRST PORT INTERMEDIATE THE ENDS THEREOF CONNECTED TO THE INTAKE OF SAID COMPRESSOR, SAID VALVE BODY HAVING A PAIR OF PORTS ON OPPOSITE SIDES OF SAID FIRST PORT CONNECTED TO SAID PAIR OF HEAT EXHANGERS, SAID VALVE BODY HAVING A PAIR OF INLET OPENINGS SPACED LONGITUDINALLY THEREOF ON OPPOSITE SIDES OF SAID PORTS, MEANS FOR SELECTIVELY CONNECTING THE DISCHARGE SIDE OF SAID COMPRESSOR TO ONE OR THE OTHER OF SAID INLET OPENINGS, A PISTON MOUNTED FOR FREE SLIDING MOVEMENT IN SAID VALVE BODY BETWEEN A PAIR OF LIMIT POSITONS SAID PISTON COOPERATING WITH SAID VALVE BODY TO FORM A CHAMBER INTERMEDIATE THE ENDS OF SAID PISTON SHAPED SO 